"Victor Sack" > wrote in message
...
> Bending the Rules on Bacteria
> By HAROLD McGEE
> International Herald Tribune
>
> PEPPERED as we are by government warnings about the potential health
> hazards of eating and drinking just about everything, it was refreshing
> (and perplexing) to see a widely respected food writer assert recently
> that "people are unnecessarily afraid of bacteria" in the kitchen.
>
> In April, Michael Ruhlman, author of "Ratio" and "The Elements of
> Cooking" and co-author of books by Thomas Keller and other chefs, said
> on his blog that he likes to make chicken stock and leave it out on the
> stovetop all week, using portions day to day to make quick soups and
> sauces.
>
> But what about the harmful microbes that could grow on foods if they
> were not kept either chilled or hot? "Once your stock is cooked, it's
> safe to eat," Mr. Ruhlman wrote. "If there were bad bacteria in it,
> you'd have killed them." After the stock has cooled, simply reheat it,
> he continued, and "any bacteria that landed there and began to multiply
> will be dispatched well before the stock hits a simmer."
>
> Sounds plausible, and Mr. Ruhlman and his family are alive and well. But
> after checking with an independent expert on food safety, I wouldn't
> follow this recipe without slapping a biohazard label on my stockpot.
>
> The Food and Drug Administration sets regulations for commercial food
> production. These specify that cooked foods should sit out at
> temperatures from 41 degrees to 135 degrees, the range in which bacteria
> can grow and multiply, for no more than four hours.
>
> Guidelines for the consumer and home cook, which come from the
> Department of Agriculture Food Safety and Inspection Service, are even
> stricter. The current brochure, "Keep Food Safe! Food Safety Basics," on
> the U.S.D.A. Web site, says not to leave prepared foods in the bacterial
> growth zone for longer than two hours. And if it's a 90-degree summer
> day, cut the two hours to one.
>
> Mr. Ruhlman's stock spends days in the bacterial growth zone, and he
> happily makes it into chicken soup for his children.
>
> I'll admit to violating the guidelines in my own stock-making, though by
> a few hours, not days. When I cook a roast for dinner, I use leftover
> scraps and bones to start the stock, simmer it while I clean up, and
> take the pot off the heat right before I go to bed. At that point it's
> too much trouble to cool the hot stock so it won't warm up its neighbors
> in the refrigerator. Instead, I cover the pot, leave it at room
> temperature and reheat it in the morning, about eight hours later,
> before straining, cooling and refrigerating it. And my stock hasn't made
> me or my family ill, either.
>
> Can I be even more relaxed about my stock-making? Or have Mr. Ruhlman
> and I just been lucky? For an expert opinion, I sent our recipes to O.
> Peter Snyder, a food scientist and veteran educator and consultant to
> the food-service industry, who has at times taken issue with government
> guidelines he considers unnecessarily conservative.
>
> Dr. Snyder replied in an e-mail: "The process described by Mr. Ruhlman
> is a very high-risk procedure. It depends totally on reheating the stock
> before it is used to be sure that it doesn't make anyone ill or possibly
> kill them."
>
> It's a basic fact that every cook should know: bacteria that cause
> illness inevitably end up on nearly every ingredient we cook with, and
> even boiling won't kill all of them.
>
> Boiling does kill any bacteria active at the time, including E. coli and
> salmonella. But a number of survivalist species of bacteria are able to
> form inactive seedlike spores. These dormant spores are commonly found
> in farmland soils, in dust, on animals and field-grown vegetables and
> grains. And the spores can survive boiling temperatures.
>
> After a food is cooked and its temperature drops below 130 degrees,
> these spores germinate and begin to grow, multiply and produce toxins.
> One such spore-forming bacterium is Clostridium botulinum, which can
> grow in the oxygen-poor depths of a stockpot, and whose neurotoxin
> causes botulism.
>
> Once they've germinated, bacteria multiply quickly in nourishing stock.
> They can double their numbers every 90 minutes at room temperature,
> every 15 minutes at body temperature. A single germinated spore can
> become 1,000 bacteria in a matter of hours, a billion in a few days.
>
> As Dr. Snyder put it, "After sitting on the stove and growing bacteria
> for two or three days, Mr. Ruhlman's stock almost certainly has high
> levels of infectious Clostridium perfringens cells, or Clostridium
> botulinum or Bacillus cereus cells and their toxins, or some combination
> thereof."
>
> Why has the Ruhlman family survived? Because Mr. Ruhlman boils the stock
> before he serves it, Dr. Snyder wrote. Any active bacteria are killed by
> holding the stock for a minute at 150 degrees or above, and botulism
> toxin is inactivated by 10 minutes at the boil.
>
> But quickly reheating a contaminated stock just up to serving
> temperature won't destroy its active bacteria and toxins, and the stock
> will make people sick.
>
> "If Mr. Ruhlman ever has a cup of his three-day-old stock without
> thoroughly boiling it first, he will probably only do it once," Dr.
> Snyder wrote. "It is irresponsible of any cook to prepare food in a way
> that actually creates a new and significant hazard, even though the
> hazard may be eliminated in a later step."
>
> Safety is one problem with keeping a stock at room temperature. Flavor
> is another. A reboiled three-day-old stock may be safe to eat, but it is
> now seasoned with millions to billions of dead bacteria and their
> inactivated toxins. It's conceivable that they might add an interesting
> flavor, but more likely that the bacteria have feasted on the stock's
> sugars and savory amino acids, the air has oxidized and staled the fat,
> and the stock has become less tasty.
>
> I spoke with Mr. Ruhlman about Dr. Snyder's analysis of his
> stovetop-stored stock. "I agree that I should have been clearer about
> the importance of the 'kill step,' a good 10 minutes at the boil," he
> said. "And certainly to make the freshest, cleanest stock, it's always
> best to strain, cool and chill it as rapidly as possible."
>
> What about my lazy method of letting stock cool overnight, then
> reboiling and refrigerating it first thing in the morning? Dr. Snyder
> gave it a pass because it would spend only a few hours below 135
> degrees, not enough time for the bacterial spores to germinate, start
> growing and reach hazardous numbers.
>
> Like meat stocks, all moist cooked foods are susceptible to being
> recolonized by survivalist bacteria. (Baked goods are generally too dry
> for bacteria; they're spoiled by molds.) That's why we should avoid
> leaving cooked foods out at room temperature for long when we're
> preparing for a party or holiday feast (or enjoying their lazy
> follow-ups), or having a picnic, or packing lunch boxes for young
> children, who along with the elderly and ill are more vulnerable. It's
> best to keep moist lunch items either cold or hot, surrounded by cold
> packs or in a thermos.
>
> What are the actual odds of getting sick from casual food handling at
> home? No one really knows. There are many variables involved, and only a
> small fraction of illnesses are reported, even to a family doctor, since
> they're usually brief. But one unambiguous and heartbreaking story can
> bring home the value of handling food carefully.
>
> In 2008, a 26-year-old Japanese mother in the Osaka region shared a meal
> of leftover fried rice with her two children, ages 1 and 2. She had
> prepared and served the rice the day before and kept it at room
> temperature.
>
> All three became ill 30 minutes after eating the leftovers, and were
> hospitalized. Both children lost consciousness, and the youngest died
> seven hours after the meal. Pathologists later reported in the journal
> Pediatrics that the rice contained a very common spore-forming
> bacterium, Bacillus cereus, along with a heat-resistant toxin that the
> bacterium tends to make on starchy foods, and that can cause vomiting
> even after being heated to the boil.
>
> It may be true that most cases of food-borne illness aren't that
> serious, and that most reported cases can be traced to foods that were
> contaminated during their production or processing. But it is also true
> that one simple mistake at home can be fatal.
>
> Even though I know this, I tend to discount specific government
> guidelines because they seem to change arbitrarily, and they don't seem
> workable in real life. This is true of the latest U.S.D.A. numbers. It's
> unrealistic to expect home cooks to chill or reheat or discard dishes
> every two hours during a dinner party, or every hour at a summer
> barbecue.
>
> Dr. Snyder agreed that official pronouncements on food safety can be
> inconsistent and self-defeating. "The F.D.A. Food Code is very
> conservatively written," he wrote. "Four hours after it's cooked is
> plenty fast enough to get food into the refrigerator." And slow enough
> to relax and enjoy the meal.
>
> Dr. Snyder added that it's safest to cool leftovers uncovered and in a
> mass no thicker than two inches, so they cool through quickly. If
> they're still hot, start the cooling on the countertop. When the
> container is no longer hot to the touch, put it in the refrigerator, and
> cover it once the food is good and cold.
>
> My own everyday approach to safety is to try to keep cooked foods either
> hot or cold until I'm ready to serve them, get leftovers in the fridge
> during the pause before dessert or soon after, and reheat leftovers that
> need it until they're boiling or steaming.
>
> This set of habits isn't dictated by an unnecessary, pleasure-killing
> fear of microbes. It simply acknowledges their inevitable presence in my
> kitchen, and the fact that both my food and anyone who eats it will be
> better off if the care I give it doesn't end with the cooking.
>
>
Michael Ruhlman and his chicken stock was kicked around on this NG quite
severely recently. Michael Ruhlman is not a cook. He is the coauthor of a
number of cookbooks, and the author of several, including "Ratio" and
"Elements of Cooking", that don't say anything.